The present invention relates to an improved spring arrangement for mattresses and to mattresses when incorporating such.
In a xe2x80x9cconventionalxe2x80x9d arrangement of springs (FIG. 1) for mattresses, the coil springs are arranged in transverse rows of spaced apart coils and the spaced springs in one row and the next adjacent row of similarly spaced coils are interconnected by a helical xe2x80x9clacingxe2x80x9d wire which runs across the width of the mattress for pairs of coils. The arrangement results in the coils being spaced apart across the width of the mattress or other article.
It is also known in such conventional constructions for a xe2x80x9czoningxe2x80x9d effect to be achieved wherein it is arranged that the diameter of the wire differs in different rows in different regions so as to thereby produce a harder sprung region in the middle of the mattress which is to receive the greater load with softer springing at the head and foot to achieve the desired effect but this construction disadvantageously requires additional wire and forming operations etc.
It is also known (FIG. 2) to arrange coil springs in rows of regularly spaced apart coils along the length of a mattress and the coils of a row (and of one adjacent row) are interconnected by a helical lacing wire in rows which runs from xe2x80x9chead-to-toexe2x80x9d i.e. along the normal length of the mattress with the result that the coil springs are regularly spaced apart along the length of the mattress and interconnected by the helical lacing wire.
Coil springs are xe2x80x9chandedxe2x80x9d i.e. left or right handed, in the same sense as a screw thread is left or right handed, and depending on the direction of coiling of the springs and such xe2x80x9chandingxe2x80x9d affects the way the springs compress and their tendency to lean over to one side. Coil springs are normally helically wound and often have a double conical winding.
Coil springs are produced from wire and the opposite otherwise free ends of the wire are secured by being bent around opposite ends of the coil to form so called xe2x80x9cknotsxe2x80x9d and such knots are on the same side of the coils (and indicated by a cross herein).
The most commonly used knotted springs are known as Bonnell springs (FIGS. 4 and 5), and such are made of right-hand helixes, for example, and similarly disposed with their knots being in the same orientation with the result that there is a tendency when being compressed along the axis of the spring (force in direction A), for the spring to fall away in one direction and to one side (arrow B) which is substantially at 90xc2x0 to the diametral plane intersecting the two knots. It is known in the conventional arrangement for all the coils to have their knots disposed in the same manner (FIG. 6) (apart from the outermost ones of each row which are reversed to avoid the sharp knot end projecting outwardly which might otherwise be a hazard to users).
According the present invention there is provided a spring arrangement for a mattress in which the springs are double conical springs with each coil spring being knotted at its opposite ends on one side or is unknotted at its opposite ends on one side and has a tendency when subject to load to bend over at another side, and wherein a plurality of rows of said spaced apart springs are provided in a head-to-toe arrangement in which the springs are disposed in adjacent rows with the coil springs in each row being spaced apart along the length of the arrangement, and wherein interconnecting or lacing wires interconnect along the length of the arrangement, the springs in a row and also the springs in the adjacent row to form rows of spaced interconnecting springs and with the coils of adjacent similar rows being juxtaposed, and in which the spacing of the springs in each of the head-to-toe rows is closer in at least one and the same region where greater support or firmer support is required, and in which either a plurality of pairs of the springs in each row of interconnected spaced apart springs are arranged so that the knotted or said unknotted sides in each pair of springs are juxtaposed or so that said one sides to which there is a tendency to bend over are oppositely disposed in said pairs or otherwise oriented to act to counteract each other, or in which the orientation of all or at least a group of springs in one row is opposite to the orientation of all or at least a group of the springs in the next or an adjacent row so as to provide rows of springs with directional counteracting tendencies to bending over in a single direction.
It is an object of the present invention to provide an improved spring arrangement and a mattress incorporating such an arrangement so as to provide more support in one or more regions, as desired, and, also to create a reduced tendency of the upper portions of the springs to move laterally in the same direction because of the creation of a greater stability of the overall arrangement and thus an improved performance.
The arrangement of the invention enables a firmer support to be provided in one or more regions as desired and whilst at least the central region of a mattress will be normally arranged to be firmer, additional or alternative regions are envisaged. Furthermore the arrangement reduces or minimises the tendency of the upper regions springs to all lean or flex to move in the same lateral direction and the spring arrangement incorporating provides improved performance. It is envisaged other orientation of the spring knotting is possible to achieve improved performance.